When we visited our friends in Duck Key we would always stop at Herbie's. 'Conch chowder and fritters are the best - not fancy, but good down home cooking in a friendly atmosphere - & reasonable.
Not well known but should be.
I plan my trips to the lower keys around when Herbies is open! The food, conch fritters in particular, is great. This is a locals spot, looks a little too "run down" to attract too many tourists. The service is great, very friendly…